nvidia-settings . . . . I know youv'e probably looked here but if not . . .

Sorry for the delay to finish up on this. It took me swapping the original motherboard for a replacement from the manufacturer along with swapping the processor with a replacement from AMD until I finally found the problem.

I had a bad RAM module.

Apparently the motherboard meltdown took the RAM with it. However, none of the motherboards I tried reported the RAM as bad in POST.

I was trying to boot Knoppix and I noticed it had a DOS-based RAM test and so I went ahead and tried that.

All in all, it took me from November to February to finally get this solved.

If you want to get SLI running, instead of manually editing the xorg.conf you should copy/paste this command.
That will add the line to your xorg.conf for Alternating Frame Rendering and you're less likely to make a mistake. Both "Yes" and "AFR" have worked for me but I would rather specify AFR because I have no idea what "YES" means to Nvidia. Alternately you can use SFR (Split Frame Rendering) or AA (Hellifino)